PoE is a technology that when an existing Ethernet cabling infrastructure is not modified, when a data signal is transmitted for some devices such as an Internet Protocol (IP) telephone, an access point (AP), and a network camera, a direct current can be supplied to these devices at the same time.
Generally, a PoE system mainly includes PSE and a powered device (PD). The PSE mainly includes a master control chip (master control) and a PSE chip, and a power supplying process of the PSE chip may be generally divided into five parts: PD detection, classification, power-on, normal power supplying, and power-off. The PSE chip first detects whether the PD is valid, then classifies the PD to determine power consumption, and powers on the PD after completion of the classification to start to supply power. During normal power supplying, the PSE chip continuously monitors a current of the PD, and when PD power consumption encounters overload or short circuit, or exceeds power supplying load of the PSE chip, the PSE chip disconnects a power supply and starts a next round of a detection process.
In the PSE of the existing PoE system, the master control manages the PSE chip using an inter-integrated circuit (IIC) bus, one PSE chip may supply power to multiple PoE ports, and each PoE port may connect to one PD. The PSE chip has four modes: an off mode in which no action is performed, a manual mode in which an external program may trigger and control detection, classification, and power-on. A semi auto mode in which detection and classification are automatically performed and the external program may control power-on, and an auto mode in which detection, classification, and power-on are automatically performed. The master control is responsible for a function such as remote management, coordination between PSE chips, power-on and power-off of a non-standard PD, or power supply management. After power is turned on, the PSE chip is in the off mode and waits for the master control to start. After the master control starts, the PSE chip is initialized and is configured to be in the semi auto mode. In this case, the PSE chip starts, under management of the master control, detection, classification, and power supplying, and the master control is further responsible for a function of PoE overall management.
Generally, a startup upon power-on process of the PSE is shown in FIG. 1. After the PSE is connected to the power supply, a central processing unit (CPU) of the master control first runs boot (BOOT) of a basic input/output system (BIOS) and initializes a double data rate (DDR) synchronous dynamic random access memory (SDRAM) to obtain relatively large memory usage space. After initialization is completed, the BIOS/BOOT checks whether a system needs to be upgraded. The BIOS/BOOT obtains a startup file using an Ethernet port, a serial port, or a local flash memory, loads an operating system (OS) from the startup file, and starts a main program if the system does not need to be upgraded, and the main program initializes various components and configures the PSE chip to be in the semi auto mode. The PSE can properly supply power under the management of the master control only after startup of the main program is completed. The main program of the master control provides abundant management functions. A user may check a port state, set a PoE alarm, set reserved power, perform forced power-on or power-off, and so on by logging in to the master control.
However, in other approaches, though the master control can flexibly manage the PD device, a startup time of the PoE system is long and a power supply speed is low, because the PD cannot obtain power before the master control completely starts, and after the master control is powered off, if power supplying is resumed, it takes a very long time for an entire network including the PD to return to normal.